At present, verification experiments of driving safety support systems (DSSS: Driving Safety Support Systems) have been carried out so as to prevent traffic accidents caused by carelessness of drivers, which occur at intersections and on approach roads to the intersections.
The DSSS, for example, are systems which provide to a driver a traffic condition around the driver in the form that may be visually and acoustically recognized (such as a display of an alerting image or an output of an alerting voice message) and call attention to a dangerous factor. Relaxed driving is thereby supported.
The DSSS include an apparatus on a road side having a transmitter (hereinafter referred to as an optical beacon unit) that transmits an optical signal, a transmitter (hereinafter referred to as a DSRC beacon unit) that transmits an electric wave of a 5.8 GHz band, and a roadside control unit (information relay and determination device).
The DSSS further include an in-vehicle unit that exchanges data with the optical beacon unit and the DSRC beacon unit.
The DSSS includes a detection sensor and a signal controller, as apparatuses on the road side. The detection sensor detects the position of a vehicle, the speed of the vehicle, the number of vehicles, the number of pedestrians, and the like, and the signal controller controls the traffic density at the intersection. A vehicle detection sensor which detects distances of a four-wheeled vehicle and an automatic two-wheeled vehicle to an intersection and running speeds of the four-wheeled and automatic two-wheeled vehicles as they enter the intersection, and a pedestrian detection sensor which detects a pedestrian walking on a crosswalk within the intersection and a bicycle running on the crosswalk, are examples of the detection sensor. The roadside control unit collects signal information from the signal controller and the detected information from the detection sensor, and transmits those information to the optical beacon unit and the DSRC beacon unit.
The optical beacon unit is installed before the intersection. The optical beacon unit transmits to the vehicle the position of a lane on which the vehicle is running and provision of a DSSS service. The optical beacon unit further provides to the vehicle static information (hereinafter referred to as fixed information) such as geographical information on the size of the intersection, presence or absence of a side road, through the in-vehicle unit.
The roadside control unit (information relay and determination device) collects information on the position of an oncoming vehicle entering the intersection, information on the speed of the oncoming vehicle, and information on the presence of the pedestrian or the bicycle on the crosswalk within the intersection, from the detection sensors. The roadside control unit further collects information on the color of a traffic light output from the signal controller. The roadside control unit also prepares, based on the collected information, traffic information (intersection information) that changes real time and transmits the prepared information to the DSRC beacon unit.
The DSRC beacon unit is installed in the vicinity of the intersection, and provides to the vehicle the traffic information that has been prepared by the roadside control unit.
Using the above-mentioned DSSS, a right-turn accident prevention service and a left-turn hit accident prevention service, for example, have been evaluated and verified.